Hip MRI findings and outcomes following imaging-guided hip injections.

OBJECTIVE: To determine if MRI findings prior to intra-articular corticosteroid hip infiltration are related to treatment outcomes. METHODS: This prospective outcome study with retrospective MRI evaluation includes 100 consecutive patients with MRI within 6 months before a therapeutic intra-articular hip injection. Labrum, bone marrow, acetabular and femoral cartilage abnormalities were assessed by two radiologists blinded to patient outcomes: the proportion reporting "improvement" on the Patient's Global Impression of Change (PGIC) scale at 1 day, 1 week and 1 month follow-up were compared based on MRI findings using χ2. The t-test was used to compare pain change scores with MRI abnormalities. RESULTS: Patients with a normal labrum in the posterosuperior quadrant were more likely to report PGIC "improvement" at 1 week compared to labral degeneration (p = 0.048). Significant differences in pain change scores were found at all time points for the labral anteroinferior quadrant (p = 0.001, 1 day; p = 0.010, 1 week; p = 0.034, 1 month) with the highest reduction in patients with labral degeneration. Females were 2.80 times more likely to report clinically relevant "improvement" at 1 day (p = .049) and 2.90 times more likely to report clinically relevant "improvement" at 1 month (p = .045). CONCLUSION: Cartilage defects and marrow abnormalities were not associated with outcomes. Patients with a normal labrum in the posterosuperior quadrant had better outcomes at 1 week. Patients with labral degeneration of the anteroinferior quadrant had higher levels of pain reduction at all time points. Females were significantly more likely to report PGIC "improvement". ADVANCES IN KNOWLEDGE: A significant treatment outcome was observed amongst gender, although there were no significant differences in the MRI findings.

Quantitative MRI of visually intact rotator cuff muscles by multiecho Dixon-based fat quantification and diffusion tensor imaging.

BACKGROUND: Quantitative MRI allows assessment of shoulder rotator cuff (RC) muscles by Dixon MR sequences with calculation of fractional fat content (FF%) maps and diffusion tensor imaging (DTI) including tractography. PURPOSE: To compare FF% and DTI derived parameters among visually intact RC muscles, to compare 2D with 3D DTI measurements and to establish normative values. STUDY TYPE: Prospective. SUBJECTS: Forty patients aged >18 years undergoing shoulder MR arthrography were included. FIELD STRENGTH/SEQUENCE: MR arthrography of the shoulder including 3D multiecho Dixon and 3D echo-planar DTI sequences (15 gradient encoding directions, b-value 600 s/mm2 ) was performed at 3.0T. ASSESSMENT: Muscles affected by RC tears or fatty infiltration of Goutallier grade ≥1 were excluded. Two independent radiologists measured FF%, apparent diffusion coefficient (ADC), and fractional anisotropy (FA) by region-of-interest (ROI) placements at the Y-position of the scapula and 3D tractography of each muscle with qualitative evaluation was performed. STATISTICAL TESTS: Intraclass correlation coefficients (ICCs) and Cohen's kappa were used for interreader agreement and Pearson correlation coefficient to correlate quantitative measures with each other and age, independent-samples t-test, one-way analysis of variance (ANOVA), and Kruskal-Wallis test were performed to investigate differences between genders and muscles. RESULTS: Qualitative and quantitative measurements showed moderate (κ = 0.41-0.56) to almost perfect (ICC = 0.75-0.99) agreement. There were weak but significant positive correlations of FF% with age (r = 0.273, P < 0.05) and FA-2D (r = 0.319-0.383, P < 0.05). Significant differences were found among RC muscles for ADC, radial diffusivity (RD), and tract homogeneity (all P < 0.05) but not between genders (all P ≥ 0.05). High correlations of 2D with 3D measurements for ADC (r = 0.639, P < 0.001) and FA (r = 0.628, P < 0.001) were seen. DATA CONCLUSION: Quantitative MRI with estimation of FF% and DTI parameters shows significant age-associated changes and differences among visually intact RC muscles. High reproducibility and correlations of 2D with 3D DTI measurements can be expected. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:109-117.

Impact of graft and tunnel orientation on patient-reported outcome in anterior cruciate ligament reconstruction using bone-patellar tendon-bone autografts.

BACKGROUND: The optimal positioning of anterior cruciate ligament graft is still controversially discussed. We therefore wanted to determine the tunnel-to-joint (TJA), tunnel-to-shaft (TSA), and graft-tunnel divergence angles which would provide the best outcome, determined by the KOOS (Knee Injury and Osteoarthritis Outcome Score). This study evaluated the clinical influence of graft orientation as measured with the KOOS questionnaire in patients with anterior cruciate ligament reconstruction with bone-patellar tendon-bone autografts. METHODS: We designed a prospective cohort study, with a 1 » year recruitment phase from March 2011 to July 2012 and a minimal follow-up period of 1 year. Inclusion criteria were patients ≥ 18 years of age receiving an ACL reconstruction with bone-patellar tendon-bone autografts at our institution after having suffered an acute ACL rupture. The primary outcome was the KOOS. Independent variables were patient age, gender, laterality of rupture, mechanism of trauma, and type of femoral and tibial fixation, as well as sagittal graft-tunnel divergence, TJA, and TSA, the latter two being assessed on coronal slices of magnetic resonance imaging. Equations modeling the relationship between TJA, TSA, and graft-tunnel divergence with the KOOS overall score were fitted, and the optimum angles were mathematically determined. RESULTS: In total, 31 patients were included in our study. Our cohort with a median age of 28 years was predominantly male. The mathematically determined optimal placement of the implant in the coronal plane was a TJA of 74.8°, a TSA of 80.1°, and a graft-tunnel divergence angle of 8.5°. CONCLUSION: With regard to patient-reported outcome, the optimal graft orientation is provided by a coronal tunnel-to-shaft angle of 80° and tunnel-to-joint angle of 75°, respectively. Interestingly, in our series, patients reported best clinical outcomes with a sagittal graft-tunnel divergence. These results should be validated in larger studies.

Shoulder muscle volume and fat content in healthy adult volunteers: quantification with DIXON MRI to determine the influence of demographics and handedness.

OBJECTIVE: We aimed to provide mean values for fat-fraction and volume for full-length bilateral rotator cuff and deltoid muscles in asymptomatic adults selected on the basis of their good musculoskeletal and systemic health, and to understand the influence of gender, age, and arm dominance. MATERIALS AND METHODS: Seventy-six volunteers aged 20 to 60 years who were screened for normal BMI and high general health were included in the study. MRI was performed at 3 Tesla using three-point DIXON sequences. Volume and fat-signal fraction of the rotator cuff muscles and the deltoid muscle were determined with semi-automated segmentation of entire muscle lengths. Differences according to age, gender, and handedness per muscle were evaluated. RESULTS: Fat-signal fractions were comparable between genders (mean ± 2 SD, 95% CI, women 7.0 ± 3.0; 6.8-7.2%, men 6.8 ± 2.7; 6.7-7.0%) but did not show convincing changes with age. Higher shoulder muscle volume and lower fat-signal fraction in the dominant arm were shown for teres minor and deltoid (p < 0.01) with similar trends shown for the other rotator cuff muscles. CONCLUSIONS: Bilateral fat-signal fractions and volumes based on entire length shoulder muscles in asymptomatic 20-60 year old adults may provide reference for clinicians. Differences shown according to arm dominance should be considered and may rationalize the need for bilateral imaging in determining appropriate management.

Whole-body adipose tissue and lean muscle volumes and their distribution across gender and age: MR-derived normative values in a normal-weight Swiss population.

PURPOSE: To determine age- and gender-dependent whole-body adipose tissue and muscle volumes in healthy Swiss volunteers in Dixon MRI in comparison with anthropometric and bioelectrical impedance (BIA) measurements. METHODS: Fat-water-separated whole-body 3 Tesla MRI of 80 healthy volunteers (ages 20 to 62 years) with a body mass index (BMI) of 17.5 to 26.2 kg/m2 (10 men, 10 women per decade). Age and gender-dependent volumes of total adipose tissue (TAT), visceral adipose tissue (VAT), total abdominal subcutaneous adipose tissue (ASAT) and total abdominal adipose tissue (TAAT), and the total lean muscle tissue (TLMT) normalized for body height were determined by semi-automatic segmentation, and correlated with anthropometric and BIA measurements as well as lifestyle parameters. RESULTS: The TAT, ASAT, VAT, and TLMT indexes (TATi, ASATi, VATi, and TLMTi, respectively) (L/m2 ± standard deviation) for women/men were 6.4 ± 1.8/5.3 ± 1.7, 1.6 ± 0.7/1.2 ± 0.5, 0.4 ± 0.2/0.8 ± 0.5, and 5.6 ± 0.6/7.1 ± 0.7, respectively. The TATi correlated strongly with ASATi (r > 0.93), VATi, BMI and BIA (r > 0.70), and TAATi (r > 0.96), and weak with TLMTi for both genders (r > -0.34). The VAT was the only parameter showing an age dependency (r > 0.32). The BMI and BIA showed strong correlation with all MR-derived adipose tissue volumes. The TAT mass was estimated significantly lower from BIA than from MRI (both genders P < .001; mean bias -5 kg). CONCLUSIONS: The reported gender-specific MRI-based adipose tissue and muscle volumes might serve as normative values. The estimation of adipose tissue volumes was significantly lower from anthropometric and BIA measurements than from MRI. Magn Reson Med 79:449-458, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Direct comparison of PI-RADS version 2 and version 1 regarding interreader agreement and diagnostic accuracy for the detection of clinically significant prostate cancer.

PURPOSE: to simultaneously evaluate interreader agreement and diagnostic accuracy in the of PI-RADS v2 and compare it to v1. METHODS: A total of 67 patients (median age 65.3 y, range 51.2-78.2 y; PSA 6.8µg/L, 0.2-33µg/L) undergoing MRI of the prostate and subsequent transperineal template biopsy within ≤6 months from MRI were included. Four readers from two institutions evaluated the likelihood of prostate cancer using PI-RADS v1 and v2 in two separate reading sessions ≥3 months apart. Interreader agreement was assessed for each pulse-sequence and for total PI-RADS scores using the intraclass correlation coefficient (ICC). Differences were considered significant for non-overlapping 95%-confidence intervals. Diagnostic accuracy was assessed with the area under the receiver operating characteristic curve (AZ). A p-value <0.05 was considered statistically significant. RESULTS: Interreader agreement for DCE-scores was good in v2 (ICC2=0.70; 95% CI: 0.66-0.74) and slightly lower in v1 (ICC1=0.64, 0.59-0.69). Agreement for DWI scores (ICC1=0.77, ICC2=0.76) as well as final PI-RADS scores per quadrant were nearly identical (ICC1=ICC2=0.71). Diagnostic accuracy showed no significant differences (p=0.09-0.93) between v1 and v2 in any of the readers (range: AZ=0.78-0.88). CONCLUSION: PI-RADS scores show similar interreader agreement in v2 and v1 at comparable diagnostic performance. The simplification of the DCE interpretation in v2 might slightly improve agreement while not negatively affecting diagnostic performance.

Functional and Structural Network Recovery after Mild Traumatic Brain Injury: A 1-Year Longitudinal Study.

Brain connectivity after mild traumatic brain injury (mTBI) has not been investigated longitudinally with respect to both functional and structural networks together within the same patients, crucial to capture the multifaceted neuropathology of the injury and to comprehensively monitor the course of recovery and compensatory reorganizations at macro-level. We performed a prospective study with 49 mTBI patients at an average of 5 days and 1 year post-injury and 49 healthy controls. Neuropsychological assessments as well as resting-state functional and diffusion-weighted magnetic resonance imaging were obtained. Functional and structural connectome analyses were performed using network-based statistics. They included a cross-sectional group comparison and a longitudinal analysis with the factors group and time. The latter tracked the subnetworks altered at the early phase and, in addition, included a whole-brain group × time interaction analysis. Finally, we explored associations between the evolution of connectivity and changes in cognitive performance. The early phase of mTBI was characterized by a functional hypoconnectivity in a subnetwork with a large overlap of regions involved within the classical default mode network. In addition, structural hyperconnectivity in a subnetwork including central hub areas such as the cingulate cortex was found. The impaired functional and structural subnetworks were strongly correlated and revealed a large anatomical overlap. One year after trauma and compared to healthy controls we observed a partial normalization of both subnetworks along with a considerable compensation of functional and structural connectivity subsequent to the acute phase. Connectivity changes over time were correlated with improvements in working memory, divided attention, and verbal recall. Neuroplasticity-induced recovery or compensatory processes following mTBI differ between brain regions with respect to their time course and are not fully completed 1 year after trauma.

Increased interreader agreement in diagnosis of hepatocellular carcinoma using an adapted LI-RADS algorithm.

PURPOSE: To evaluate a simplified Liver Imaging Reporting and Data System (LI-RADS) algorithm to improve interreader agreement while maintaining diagnostic performance for HCC. MATERIALS AND METHODS: MRI scans of 84 cirrhotic patients with 104 distinct liver observations were retrospectively selected to equivocally match each of the LI-RADS grades (LR1-5) using histopathology and imaging follow up as standard of reference. Four independent radiologists categorized all observations as benign (LR1-2) or potentially malignant (LR3-5) and determined LI-RADS based imaging features including observation size, arterial phase hyperenhancement, washout, capsule appearance and threshold growth for LR3-5 observations and timed their readouts. LR3-5 observations were categorized according to the LI-RADS v2014 algorithm and according to a modified LI-RADS (mLI-RADS) version. Diagnostic performance and Interreader agreement were determined for LI-RADS and mLI-RADS using receiver operating characteristics (ROC) and Fleiss' and Cohen's Kappa analysis respectively. RESULTS: ROC analysis revealed equal diagnostic performance for LI-RADS and mLI-RADS (area under the ROC curve=0.91). Interreader agreement was higher using mLI-RADS as compared to current LI-RADS showing an improved overall (κ=0.53±0.04 vs. 0.45±0.04), and pair-wise agreement between most readers (κ range 0.44-0.62 vs. 0.35-0.60) at a reduced median evaluation time (51 vs. 62s per observation, p<0.0001). CONCLUSION: Focusing on observation size and washout criteria using a modified, stepwise LI-RADS decision tree for LR3-5 observations results in higher interobserver reliability and faster categorization while maintaining diagnostic accuracy.

Association between traumatic bone marrow abnormalities of the knee, the trauma mechanism and associated soft-tissue knee injuries.

OBJECTIVES: To determine the association between traumatic bone marrow abnormalities, the knee injury mechanism, and associated soft tissue injuries in a larger cohort than those in the published literature. METHOD: Retrospective study including 220 patients with traumatic knee injuries. Knee MRIs were evaluated for trauma mechanism, soft tissue injury, and the location of bone marrow abnormalities. The locations of the abnormalities were correlated with trauma mechanisms and soft tissue injuries using the chi-square test with Bonferroni correction. RESULTS: One hundred and forty-four valgus injuries, 39 pivot shift injuries, 25 lateral patellar dislocations, 8 hyperextensions, and 4 dashboard injuries were included. Valgus and pivot shift injuries showed traumatic bone marrow abnormalities in the posterolateral regions of the tibia. Abnormalities after patellar dislocation were found in the anterolateral and centrolateral femur and patella. Hyperextension injuries were associated with abnormalities in almost all regions, and dashboard injuries were associated with changes in the anterior regions of the tibia and femur. CONCLUSIONS: Our study provides evidence of associations between traumatic bone marrow abnormality patterns and different trauma mechanisms in acute knee injury, and reveals some overlap, especially of the two most common trauma mechanisms (valgus and pivot shift), in a large patient cohort. KEY POINTS: • Specific bone marrow oedema patterns after knee trauma were confirmed. • New associations between bone marrow oedema patterns and knee trauma were shown. • Bone marrow oedema patterns help in identifying associated soft tissue injuries.

C-arm flat-panel CT arthrography of the shoulder: Radiation dose considerations and preliminary data on diagnostic performance.

OBJECTIVES: To investigate radiation dose and diagnostic performance of C-arm flat-panel CT (FPCT) versus standard multi-detector CT (MDCT) shoulder arthrography using MRI-arthrography as reference standard. METHODS: Radiation dose of two different FPCT acquisitions (5 and 20 s) and standard MDCT of the shoulder were assessed using phantoms and thermoluminescence dosimetry. FPCT arthrographies were performed in 34 patients (mean age 44 ± 15 years). Different joint structures were quantitatively and qualitatively assessed by two independent radiologists. Inter-reader agreement and diagnostic performance were calculated. RESULTS: Effective radiation dose was markedly lower in FPCT 5 s (0.6 mSv) compared to MDCT (1.7 mSv) and FPCT 20 s (3.4 mSv). Contrast-to-noise ratios (CNRs) were significantly (p < 0.05) higher in FPCT 20-s versus 5-s protocols. Inter-reader agreements of qualitative ratings ranged between к = 0.47-1.0. Sensitivities for cartilage and rotator cuff pathologies were low for FPCT 5-s (40 % and 20 %) and moderate for FPCT 20-s protocols (75 % and 73 %). FPCT showed high sensitivity (81-86 % and 89-99 %) for bone and acromioclavicular-joint pathologies. CONCLUSION: Using a 5-s protocol FPCT shoulder arthrography provides lower radiation dose compared to MDCT but poor sensitivity for cartilage and rotator cuff pathologies. FPCT 20-s protocol is moderately sensitive for cartilage and rotator cuff tendon pathology with markedly higher radiation dose compared to MDCT. KEY POINTS: • FPCT shoulder arthrography is feasible with fluoroscopy and CT in one workflow. • A 5-s FPCT protocol applies a lower radiation dose than MDCT. • A 20-s FPCT protocol is moderately sensitive for cartilage and tendon pathology.

Reliability, Validity, and Reader Acceptance of LI-RADS-An In-depth Analysis.

RATIONALE AND OBJECTIVES: This study aimed to analyze interreader agreement and diagnostic accuracy of Liver Imaging Reporting and Data System (LI-RADS) in comparison to a nonstandardized 5-point scale and to assess reader acceptance of LI-RADS for clinical routine. MATERIALS AND METHODS: Eighty-four consecutive patients at risk for hepatocellular carcinoma who underwent liver magnetic resonance imaging were included in this Health Insurance Portability and Accountability Act-compliant retrospective study. Four readers rated the likelihood of hepatocellular carcinoma for 104 liver observations using LI-RADS criteria and a 5-point Likert scale (LIKERT) based on subjective impression in two separate reading sessions. Interreader agreement was assessed using kappa statistics (κ). Diagnostic accuracy was assessed with receiver operating characteristic analysis. Reader acceptance was evaluated with a questionnaire. A sub-analysis of LI-RADS's major features (arterial phase hyper-enhancement, washout, capsule appearance, and threshold growth) and scores for lesions 1.5 cm was performed. RESULTS: LI-RADS showed similar overall interreader agreement compared to LIKERT (κ, 0.44 [95%CI: 0.37, 0.52] and 0.35 [95%CI: 0.27, 0.43]) with a tendency toward higher interreader agreement for LI-RADS. Interreader agreement (κ) was 0.51 (95%CI: 0.38, 0.65) for arterial phase hyper-enhancement, 0.52 (95%CI: 0.39, 0.65) for washout, 0.37 (95%CI: 0.23, 0.52) for capsule appearance, and 0.50 (95%CI: 0.38, 0.61) for threshold growth. Overall interreader agreement for LI-RADS categories was similar between observations <1.5 cm and observations >1.5 cm. Overall diagnostic accuracy for LIKERT and LI-RADS was comparable (area under the receiver operating characteristic curve, 0.86 and 0.87). Readers fully agreed with the statement "A short version of LI-RADS would facilitate the use in clinical routine" (median, 5.0; interquartile range, 2.25). CONCLUSIONS: LI-RADS showed similar interreader agreement and diagnostic accuracy compared to nonstandardized reporting. However, further reduction of complexity and refinement of imaging features may be needed.

Connectomic and Surface-Based Morphometric Correlates of Acute Mild Traumatic Brain Injury.

Reduced integrity of white matter (WM) pathways and subtle anomalies in gray matter (GM) morphology have been hypothesized as mechanisms in mild traumatic brain injury (mTBI). However, findings on structural brain changes in early stages after mTBI are inconsistent and findings related to early symptoms severity are rare. Fifty-one patients were assessed with multimodal neuroimaging and clinical methods exclusively within 7 days following mTBI and compared to 53 controls. Whole-brain connectivity based on diffusion tensor imaging was subjected to network-based statistics, whereas cortical surface area, thickness, and volume based on T1-weighted MRI scans were investigated using surface-based morphometric analysis. Reduced connectivity strength within a subnetwork of 59 edges located predominantly in bilateral frontal lobes was significantly associated with higher levels of self-reported symptoms. In addition, cortical surface area decreases were associated with stronger complaints in five clusters located in bilateral frontal and postcentral cortices, and in the right inferior temporal region. Alterations in WM and GM were localized in similar brain regions and moderately-to-strongly related to each other. Furthermore, the reduction of cortical surface area in the frontal regions was correlated with poorer attentive-executive performance in the mTBI group. Finally, group differences were detected in both the WM and GM, especially when focusing on a subgroup of patients with greater complaints, indicating the importance of classifying mTBI patients according to severity of symptoms. This study provides evidence that mTBI affects not only the integrity of WM networks by means of axonal damage but also the morphology of the cortex during the initial post-injury period. These anomalies might be greater in the acute period than previously believed and the involvement of frontal brain regions was consistently pronounced in both findings. The dysconnected subnetwork suggests that mTBI can be conceptualized as a dysconnection syndrome. It remains unclear whether reduced WM integrity is the trigger for changes in cortical surface area or whether tissue deformations are the direct result of mechanical forces acting on the brain. The findings suggest that rapid identification of high-risk patients with the use of clinical scales should be assessed acutely as part of the mTBI protocol.

Comparison of a 32-channel head coil and a 2-channel surface coil for MR imaging of the temporomandibular joint at 3.0 T.

OBJECTIVE: To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using a standard TMJ surface coil and a head coil at 3.0 T. METHODS: 22 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) and a 32-channel head coil at 3.0 T (Philips Ingenia; Philips Healthcare, Netherlands). Imaging protocol consisted of an oblique sagittal proton density weighted turbo spin echo sequence (repetition time/echo time, 2700/26 ms). For quantitative assessment, a spherical phantom was imaged using the same sequence including a noise scan and a B1+ scan. Signal-to-noise ratio (SNR) maps and B1+ maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of both TMJs with the jaw in the closed position. Two independent blinded readers assessed accuracy of TMJ anatomical representation and overall image quality on a 5-point scale. Quantitative and qualitative measurements were compared between coils using t-tests and Wilcoxon signed-rank test, respectively. RESULTS: Quantitative analysis showed similar B1+ and significantly higher SNR for the head coil than the TMJ surface coil. Qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the articular disc, bilaminar zone and lateral pterygoid muscle. Furthermore, better overall image quality was observed for the head coil than for the TMJ surface coil. CONCLUSIONS: A 32-channel head coil is preferable to a standard 2-channel TMJ surface coil when imaging the TMJ at 3.0 T, because it yields higher SNR, thus increasing accuracy of the anatomical representation of the TMJ.

Effect of Gd-DOTA on fat quantification in skeletal muscle using two-point Dixon technique - preliminary data.

PURPOSE: To assess differences in fat signal fraction (FSF) in skeletal muscle as determined by two-point Dixon technique at 3T before and after application of intravenous gadoterate meglumide (Gd-DOTA). MATERIALS AND METHODS: Eight patients (mean age, 50.8 years; range, 41-72 years) underwent clinical whole-body MRI at 3T for myopathic symptoms. Two-point Dixon technique based T1-weighted turbo spin-echo images were acquired before and after the administration of intravenous Gd-DOTA. On both image sets, the FSF was calculated in the gluteus medius, gluteus maximus, and quadriceps muscles bilaterally. Pre- and post-contrast FSF values were compared by linear regression, Bland-Altman plot as well as paired Student t-tests with Bonferroni correction. RESULTS: The mean pre- and post-contrast FSF of included muscles were 28.7%±14.9% and 27.8%±15.1%, respectively. Linear regression indicated almost equivalent FSF estimation between pre- and post-contrast measurements (sum of squared residuals R(2), 0.92±0.04; slope, 0.97; X-intercept, -0.05; Y-intercept, +0.05). The Bland-Altman plot revealed a minimal systematical bias of the post-contrast FSF measurements of -0.87%. Paired Student t-tests did not reveal significant differences (overall p-value, 0.168). CONCLUSION: Gd-DOTA does not significantly influence FSF quantification in skeletal muscle based on the two-point Dixon technique at 3T.

Normative values for volume and fat content of the hip abductor muscles and their dependence on side, age and gender in a healthy population.

OBJECTIVE: To determine normative values for volume and fat content of the gluteus medius (GMed) and minimus (GMin) muscle in healthy volunteers and to evaluate their dependence on age, gender and leg dominance. MATERIALS AND METHODS: The IRB approval was obtained for this study. 80 healthy volunteers (females, 40; males, 40; age range 20-62 years), divided into four age groups, were included. Fat- and water-signal-separated MR images of the pelvis were acquired on a 3.0 T MR with a 3-point mDIXON sequence. Normalized volume and fat-signal fraction (FSF) of the GMed (ViGMed, FSFGMed) and GMin (ViGMin, FSFGMin) muscles were determined. RESULTS: The overall mean volumes (normalized) and FSF ± SD: ViGMed 105.13 ± 16.30 cm(3); ViGMin 30.24 ± 5.15 cm(3); FSFGMed 8.13 ± 1.70 % and FSFGMin 9.89 ± 2.72 %. Comparing different age subgroups within each gender no significant differences were found concerning the volumes and FSFs (except FSFGMin in male subgroup aged 20-29 versus 50-62 years, P = 0.014). Comparing FSFs differences between the two genders, only in 20-29 years subgroup, FSFGMed (P =0.003) and FSFGMin (P =0.002) were greater in female. Volume differences between the two legs were not significant (P > 0.077); FSFGMed and FSFGMin (P =0.005 for both) were significantly lower in the dominant leg in female but not in male group (P = 0.454 for FSFGMed and P = 0.643 for FSFMin). CONCLUSION: No age dependency was evident for volume normative data for GMed and GMin and normative data for FSF values showed no age- or gender dependency.

Quantitative and qualitative comparison of MR imaging of the temporomandibular joint at 1.5 and 3.0 T using an optimized high-resolution protocol.

OBJECTIVES: To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using an optimized high-resolution protocol at 3.0 T and a clinical standard protocol at 1.5 T. METHODS: A phantom and 12 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) at 1.5 and 3.0 T (Philips Achieva and Philips Ingenia, respectively; Philips Healthcare, Best, Netherlands). Imaging protocol consisted of coronal and oblique sagittal proton density-weighted turbo spin echo sequences. For quantitative evaluation, a spherical phantom was imaged. Signal-to-noise ratio (SNR) maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of the TMJ with the jaw in closed position. Two readers independently assessed visibility and delineation of anatomical structures of the TMJ and overall image quality on a 5-point Likert scale. Quantitative and qualitative measurements were compared between field strengths. RESULTS: The quantitative analysis showed similar SNR for the high-resolution protocol at 3.0 T compared with the clinical protocol at 1.5 T. The qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the TMJ disc and pterygoid muscle as well as better overall image quality at 3.0 T than at 1.5 T. CONCLUSIONS: The presented results indicate that expected gains in SNR at 3.0 T can be used to increase the spatial resolution when imaging the TMJ, which translates into increased visibility and delineation of anatomical structures of the TMJ. Therefore, imaging at 3.0 T should be preferred over 1.5 T for imaging the TMJ.

Age- and Gender Dependent Liver Fat Content in a Healthy Normal BMI Population as Quantified by Fat-Water Separating DIXON MR Imaging.

OBJECTIVES: To establish age- and sex-dependent values of magnetic resonance (MR) liver fat-signal fraction (FSF) in healthy volunteers with normal body-mass index (BMI). METHODS: 2-point mDIXON sequences (repetition time/echo time, 4.2msec/1.2msec, 3.1msec) at 3.0 Tesla MR were acquired in 80 healthy volunteers with normal BMI (18.2 to 25.7 kg/m2) between 20 and 62 years (10 men/10 women per decade). FSF was measured in 5 liver segments (segment II, III, VI, VII, VIII) based on mean signal intensities in regions of interest placed on mDIXON-based water and fat images. Multivariate general linear models were used to test for significant differences between BMI-corrected FSF among age subgroups. Pearson and Spearman correlations between FSF and several body measures were calculated. RESULTS: Mean FSF (%) ± standard deviations significantly differed between women (3.91 ± 1.10) and men (4.69 ± 1.38) and varied with age for women/men (p-value: 0.002/0.027): 3.05 ± 0.49/3.74 ± 0.60 (age group 20-29), 3.75 ± 0.66/4.99 ± 1.30 (30-39), 4.76 ± 1.16/5.25 ± 1.97 (40-49) and 4.09 ± 1.26/4.79 ± 0.93 (50-62). FSF differences among age subgroups were significant for women only (p = 0.003). CONCLUSIONS: MR-based liver fat content is higher in men and peaks in the fifth decade for both genders.

Cross-sectional area measurements versus volumetric assessment of the quadriceps femoris muscle in patients with anterior cruciate ligament reconstructions.

OBJECTIVE: Our aim was to validate the use of cross-sectional area (CSA) measurements at multiple quadriceps muscle levels for estimating the total muscle volume (TMV), and to define the best correlating measurement level. METHODS: Prospective institutional review board (IRB)-approved study with written informed patient consent. Thighs of thirty-four consecutive patients with ACL-reconstructions (men, 22; women, 12) were imaged at 1.5-T using three-dimensional (3D) spoiled dual gradient-echo sequences. CSA was measured at three levels: 15, 20, and 25 cm above the knee joint line. TMV was determined using dedicated volumetry software with semiautomatic segmentation. Pearson's correlation and regression analysis (including standard error of the estimate, SEE) was used to compare CSA and TMV. RESULTS: The mean ± standard deviation (SD) for the CSA was 60.6 ± 12.8 cm(2) (range, 35.6-93.4 cm(2)), 71.1 ± 15.1 cm(2) (range, 42.5-108.9 cm(2)) and 74.2 ± 17.1 cm(2) (range, 40.9-115.9 cm(2)) for CSA-15, CSA-20 and CSA-25, respectively. The mean ± SD quadriceps' TMV was 1949 ± 533.7 cm(3) (range, 964.0-3283.0 cm(3)). Pearson correlation coefficient was r = 0.835 (p < 0.01), r = 0.906 (p < 0.01), and r = 0.956 (p < 0.01) for CSA-15, CSA-20 and CSA-25, respectively. Corresponding SEE, expressed as percentage of the TMV, were 15.2%, 11.6% and 8.1%, respectively. CONCLUSION: The best correlation coefficient between quadriceps CSA and TMV was found for CSA-25, but its clinical application to estimate the TMV is limited by a relatively large SEE. KEY POINTS: • Cross-sectional area was used to estimate QFM size in patients with ACL-reconstruction • A high correlation coefficient exists between quadriceps CSA and volume • Best correlation was seen 25 cm above the knee joint line • A relatively large standard error of the estimate limits CSA application.

Quantitative and qualitative MR-imaging assessment of vastus medialis muscle volume loss in asymptomatic patients after anterior cruciate ligament reconstruction.

BACKGROUND: To quantitatively and qualitatively assess vastus medialis muscle atrophy in asymptomatic patients with anterior cruciate ligament reconstruction, using the nonoperated leg as control. METHODS: Prospective Institutional Review Board approved study with written informed patient consent. Thirty-three asymptomatic patients (men, 21; women,12) with ACL-reconstruction underwent MR imaging of both legs (axial T1-weighted spin-echo and 3D spoiled dual gradient-echo sequences). Muscle volume and average fat-signal fraction (FSF) of the vastus medialis muscles were measured. Additionally, Goutallier classification was used to classify fatty muscle degeneration. Significant side differences were evaluated using the Wilcoxon test and, between volumes and FSF, using student t-tests with P-value < 0.05 and < 0.025, respectively. RESULTS: The muscle volume was significantly smaller in the operated (mean ± SD, 430.6 ± 119.6 cm(3) ; range, 197.3 to 641.7 cm(3) ) than in the nonoperated leg (479.5 ± 124.8 cm(3) ; 261.4 to 658.9 cm(3) ) (P < 0.001). Corresponding FSF was 6.3 ± 1.5% (3.9 to 9.2%) and 5.8 ± 0.9% (4.0 to 7.4%), respectively, with a nonsignificant (P > 0.025) difference. The relative muscle-volume and FSF differences were -10.1 ± 8.6% (7.1 to -30.1%) and 10.9 ± 29.4% (39.7 to 40.1%). The qualitative assessment revealed no significant differences (P > 0.1). CONCLUSION: A significant muscle volume loss of the vastus medialis muscle does exist in asymptomatic patients with ACL-reconstruction, but without fatty degeneration.

Normative MR cervical spinal canal dimensions.

PURPOSE: To provide normal values of the cervical spinal canal and spinal cord dimensions in several planes with respect to spinal level, age, sex, and body height. MATERIALS AND METHODS: This study was approved by the institutional review board; all individuals provided signed informed consent. In a prospective multicenter study, two blinded raters independently examined cervical spine magnetic resonance (MR) images of 140 healthy volunteers who were white. The midsagittal diameters and areas of spinal canal and spinal cord, respectively, were measured at the midvertebral levels of C1, C3, and C6. A multivariate general linear model described the influence of sex, body height, age, and spinal level on the measured values. RESULTS: There were differences for sex, spinal level, interaction between sex and level, and body height, while age had significant yet limited influence. Normative ranges for the sagittal diameters and areas of spinal canal and spinal cord were defined at C1, C3, and C6 levels for men and women. In addition to a calculation of normative ranges for a specific sex, spinal level, age, and body height data, data for three different height subgroups at 45 years of age were extracted. These results show a range of the spinal canal dimensions at C1 (from 10.7 to 19.7 mm), C3 (from 9.4 to 17.2 mm), and C6 (from 9.2 to 16.8 mm) levels. CONCLUSION: The dimensions of the cervical spinal canal and cord in healthy individuals are associated with spinal level, sex, age, and height. Online supplemental material is available for this article.